Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segment	Jun. 30, 2015 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items]
Number of reportable segments | segment			3
Net sales:	$ 263,099	$ 253,171	$ 496,776	$ 453,786
Income (loss) from operations:	66,204	44,119	116,360	74,034
Unallocated Corporate Expenses	(8,795)	(7,064)	(15,058)	(12,233)
Total income from operations	25,777	11,201	39,384	20,171
Residential Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	119,965	134,669	220,112	241,464
Income (loss) from operations:	20,725	11,910	32,956	24,043
Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	81,380	101,900	161,397	196,185
Income (loss) from operations:	6,190	5,356	9,516	7,362
Renewable Energy & Conservation
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	62,127	17,084	116,007	17,084
Income (loss) from operations:	7,657	999	11,970	999
Intersegment Elimination
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	(373)	(482)	(740)	(947)
Intersegment Elimination | Industrial and Infrastructure Products
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net sales:	$ 81,007	$ 101,418	$ 160,657	$ 195,238